update v1.0.4

vendor/symfony/yaml/Inline.php

@@ -52,7 +52,7 @@ class Inline
             return '';
         }
 
-        if (function_exists('mb_internal_encoding') && ((int) ini_get('mbstring.func_overload')) & 2) {
+        if (2 /* MB_OVERLOAD_STRING */ & (int) ini_get('mbstring.func_overload')) {
             $mbEncoding = mb_internal_encoding();
             mb_internal_encoding('ASCII');
         }
@@ -204,6 +204,8 @@ class Inline
      * @return string A YAML string
      *
      * @throws ParseException When malformed inline YAML string is parsed
+     *
+     * @internal
      */
     public static function parseScalar($scalar, $delimiters = null, $stringDelimiters = array('"', "'"), &$i = 0, $evaluate = true, $references = array())
     {
@@ -234,6 +236,11 @@ class Inline
                 throw new ParseException(sprintf('Malformed inline YAML string (%s).', $scalar));
             }
 
+            // a non-quoted string cannot start with @ or ` (reserved) nor with a scalar indicator (| or >)
+            if ($output && ('@' === $output[0] || '`' === $output[0] || '|' === $output[0] || '>' === $output[0])) {
+                throw new ParseException(sprintf('The reserved indicator "%s" cannot start a plain scalar; you need to quote the scalar.', $output[0]));
+            }
+
             if ($evaluate) {
                 $output = self::evaluateScalar($output, $references);
             }